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R. Singh et al.
Ga 2 O 3 polymorphs, β-Ga 2 O 3 is most thermally stable and widely studied as well
as reported. Apart from an edge on high-quality native-substrate over existing GaN
technology, β-Ga 2 O 3 offers other promising features relating to power device applications, such as large bandgap of 4.9 eV and critical electric field up to 8 MV/cm. This
high critical electric field enables significant improvement in the performance of the
β-Ga 2 O 3 based high-voltage Schottky rectifiers and enhancement mode (e-mode)
metal–oxide–semiconductor field-effect transistors (MOSFETs) over SiC and GaN
power devices. Nonetheless, β-Ga 2 O 3 also faces some issues such as relatively low
electron mobility that limits DC and on-state performance, the high thermal resistance of the material requires device level thermal management and absence of p-type
doping restricts device structure types. In this chapter the overview of state-of-the-art
β-Ga 2 O 3 technologies as a supplement to existing SiC or GaN counterparts with a
perspective on the growth and development of β-Ga 2 O 3 heterostructure is presented.
The device design, microwave, and millimeter-wave (mmW) performance as well as
challenges are also presented.
Keywords FET · Gallium oxide · Heterostructure · Microwave ·
Millimeter-wave · Ultra-wide bandgap
1 Introduction
Apart from the new addition of power generation capacity to match ever increasing
worldwide energy demands, improving efficiency of power devices is equally important as it enables a significant reduction of power consumption in a wide variety of
power converters. More matured silicon (Si) technology hugely underperforms on
this front since most of the power consumed in intermediate processing. Over the
years, wide bandgap semiconductors such as SiC and GaN have been explored and are
currently in the development stage for commercial usage, for high-power and highfrequency power devices due to their suitable material properties [1]. However, some
critical issues like producing high-quality, large-size native-substrate still remains a
challenge in GaN technology [2]. Furthermore, new application areas like electric
vehicles (EV) and automation require introduction of new semiconductor devices
capable to operate at multiple kVs [3].
Recently, research community for high-voltage applications has shown great
interest in UWB semiconductors like Ga 2 O 3 , AlN, and diamond [1]. Table 1 shows
the UWB physical properties together with those for wide bandgap semiconductor,
GaN. Considering major properties of these UWB materials suitable for practical
applications, Ga 2 O 3 emerges as the ultimate choice and looks promising for future
power device applications. Out of the five different phases of Ga 2 O 3 , β phase of
Ga 2 O 3 with monoclinic structure is the most thermally stable and widely studied as
well as reported [4–8]. It has large energy bandgap values, between 4.5 to 4.9 eV as
reported in [9–11]. These values are much larger than those for wide bandgap semiconductors SiC (3.3 eV) and GaN (3.4 eV). Due to the large bandgap, the estimated
R. Singh et al.
Ga 2 O 3 polymorphs, β-Ga 2 O 3 is most thermally stable and widely studied as well
as reported. Apart from an edge on high-quality native-substrate over existing GaN
technology, β-Ga 2 O 3 offers other promising features relating to power device applications, such as large bandgap of 4.9 eV and critical electric field up to 8 MV/cm. This
high critical electric field enables significant improvement in the performance of the
β-Ga 2 O 3 based high-voltage Schottky rectifiers and enhancement mode (e-mode)
metal–oxide–semiconductor field-effect transistors (MOSFETs) over SiC and GaN
power devices. Nonetheless, β-Ga 2 O 3 also faces some issues such as relatively low
electron mobility that limits DC and on-state performance, the high thermal resistance of the material requires device level thermal management and absence of p-type
doping restricts device structure types. In this chapter the overview of state-of-the-art
β-Ga 2 O 3 technologies as a supplement to existing SiC or GaN counterparts with a
perspective on the growth and development of β-Ga 2 O 3 heterostructure is presented.
The device design, microwave, and millimeter-wave (mmW) performance as well as
challenges are also presented.
Keywords FET · Gallium oxide · Heterostructure · Microwave ·
Millimeter-wave · Ultra-wide bandgap
1 Introduction
Apart from the new addition of power generation capacity to match ever increasing
worldwide energy demands, improving efficiency of power devices is equally important as it enables a significant reduction of power consumption in a wide variety of
power converters. More matured silicon (Si) technology hugely underperforms on
this front since most of the power consumed in intermediate processing. Over the
years, wide bandgap semiconductors such as SiC and GaN have been explored and are
currently in the development stage for commercial usage, for high-power and highfrequency power devices due to their suitable material properties [1]. However, some
critical issues like producing high-quality, large-size native-substrate still remains a
challenge in GaN technology [2]. Furthermore, new application areas like electric
vehicles (EV) and automation require introduction of new semiconductor devices
capable to operate at multiple kVs [3].
Recently, research community for high-voltage applications has shown great
interest in UWB semiconductors like Ga 2 O 3 , AlN, and diamond [1]. Table 1 shows
the UWB physical properties together with those for wide bandgap semiconductor,
GaN. Considering major properties of these UWB materials suitable for practical
applications, Ga 2 O 3 emerges as the ultimate choice and looks promising for future
power device applications. Out of the five different phases of Ga 2 O 3 , β phase of
Ga 2 O 3 with monoclinic structure is the most thermally stable and widely studied as
well as reported [4–8]. It has large energy bandgap values, between 4.5 to 4.9 eV as
reported in [9–11]. These values are much larger than those for wide bandgap semiconductors SiC (3.3 eV) and GaN (3.4 eV). Due to the large bandgap, the estimated